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Region 8

Air Monitoring

Air monitoring is generally performed by State, Local, and Tribal Agencies at federally required locations or other locations with suspected high concentrations. EPA, State, Local and Tribal agencies may also monitor air in areas where the public has complaints or concerns. Agencies planning to use air pollution measurements for regulatory purposes (monitoring of National Ambient Air Quality Standard pollutants) operate EPA reference or equivalent methods and develop and follow approved quality assurance procedures. Visit EPA's AirExplorer site to view dynamic air quality charts, graphs and data tables.

Air toxics monitoring in Region 8 focuses on the measurement of hazardous air pollutants (HAPs) that are known or suspected to cause cancer or other serious health effects through the National Air Toxics Trend Station (NATTS) Network and specialized local air toxics studies. The goals of these programs are to collect air toxics data for determining basic air toxic trends and exposure assessments and for conducting air quality model evaluations.

Where are air toxics monitored in Region 8?

Currently there are 4 air toxic monitoring stations in Region 8 (2 NATTS and 2 local-scale studies monitoring sites).

NATTTS Monitoring Stations: Local Study Monitoring Stations:
Bountiful, Utah Custer Park, South Dakota
Grand Junction, Colorado Sioux Falls, South Dakota

Of the 188 HAPs regulated under Section 112 of the Clean Air Act, a reduced "core" target list of 19 compounds was selected to focus on priority compounds as shown below.

Volatile Organic Compounds
(Inorganic Compounds)
(Carbonyl Compounds)
benzene arsenic acetaldehyde
1,3-butadiene beryllium formaldehyde
carbon tetrachloride cadmium acrolein
chloroform chromium  
(propylene dichloride)
methylene chloride
vinyl chloride    

Hexavalent chromium rather than total chromium was determined to be of interest from a risk standpoint and, therefore, replaced total chromium on the core list. In addition, through other studies, measurement of black carbon has been added, primarily at the urban NATTS sites. For more information on the air toxics please visit the EPA Air Toxics Web site.

Sampling Methodologies

HAPs sampling is conducted on an every 6-day schedule for 24 hours, midnight to midnight, following the National Monitoring Schedule using VOC methods found in Compendium Method TO-15, carbonyl compound methods found in Compendium Method TO-11A, and PM10 metals found in Compendium Method IO-3-5.

Aerosol Black Carbon is a primary emission from combustion sources. Black carbon (BC) is ubiquitous and absorbs light. BC will be measured using an Aethalometer™, which is a semi-continuous instrument that measures BC using a continuous filtration and optical transmission technique.

Data Access

Although there is a delay in reporting data to the Air Quality System database (due to the Quality Assurance process), the most recent data collected can be publicly viewed via the EPA AirData Web site. Select Reports and Maps and the geographic area by county, state, region or US. Then select the HAPs Monitor Locator for a map of measurement locations or the HAPs Monitor Values or HAPs Monitor Count Reports for air toxics data.